Patent GB-471510-A (GB)
Title: Improvements in and relating to aircraft having rotative sustaining-means
IPC: B64C27/41
Filed: 1936-01-01
Abstract: 471,510. Aircraft with rotary-wing systems. CAMERON, P. Jan. 1, 1936, No. 25. [Class 4] A rotary-wing aircraft comprises a rotor head, a driven member, a one-way drive forming a coupling between the head and driven member, a driving member mounted in fixed bearing, the driving and driven members forming a driving connection which permits the head to partake of a limited universal tilting movement relative to the driving member while being driven thereby. The rotor head comprises a two-part casing 1, Fig. 2, journalled by bearings 4, 5 on a driving shaft 3 to which is keyed one element 7 of a one-way drive device of which the other element 8 is bolted to casing 1. Three blades are secured to the rotor head by hinge members 21. Each member 21 is carried by a cylindrical member 22 rotatably mounted about a radial axis in bearings 23. Member 22 is recessed to receive the disc-like end of member 21 and is provided with lugs 24. A hollow pin 25 extends through member 22, member 21, and lugs 24. The blade is thus capable of flapping movement limited by stops 21a bearing on member 22. The connection between the blade and hinge member 21 is by a vertical pivot pin 26. Swinging movement of the blade in the plane of rotation is damped by a device 28 and is limited by means of a pin 29a engaging the ends of an arcuate slot formed in blade fork 27. Blade pitch control means comprise upwardly extending arms 30 formed on members 22 and each provided with a pin 31 having a sleeve 32 received within a slot 33 formed in head 33a of an axially movable spindle 34 concentric with driving shaft 3. Spindle 34 is caused to rotate with head 1 by engagement of an extension 35 engaging splines formed in a head portion 36. Splines 35 are of spiral form so that reciprocation of spindle 34 produces rotation of blade hinge members 22. Means for extending and retracting the blades as described in Specification 471,509 comprise a flexible shaft 20 passing through apertures in the pivot pins and keyed to bevel pinions 12 meshed with upper and lower bevel pinions 13, adapted to be selectively clutched to a hollow shaft 14 disposed coaxially with driving shaft 3. At its lower end driving shaft 3 is keyed to the inner element of a self-aligning bearing 37, Fig. 3, the outer element of which is located in a driving gear 38 journalled in a two-part housing 41, 43 fixed to the aircraft frame, Fig. 1.. Shaft 3 is fitted with a retaining collar 47 adapted to engage the inner bearing element. Keyed to shaft 3 is a hemispherical member 45 having a series of fingers 45a engaging an annular series of fingers or ribs 45b driven by gear 38. Member 45 is located between a part-spherical retaining wall 43a and the inner race of self-aligning bearing 37. Means for controlling rotor tilt comprise a ring 46 journalled on shaft 3 and spring-urged to a neutral position in frame 44 by springs 46d secured to the ring itself and to semicircular members 46c arranged on either side thereof. Ring 46 and, hence, the rotor head can be tilted in any direction in a control column 65. Pitch control spindle 34 is moved axially by means of a lever 59 adapted to be rocked by screw-and-nut gear and engaging a grooved pulley 58 secured to spindle 34. The screw is rotated by a hand lever 64, Fig. 1, and flexible drive 63. A pitch angle indicator 67 is provided. Rotor extending and retracting control spindle 14 is provided at its lower end with a pulley 49 engaging a rockable lever 50, and with a brake drum 54 encircled by a brake band 55. In order to extend or retract the blades, spindle 14 is first moved axially by operation of hand lever 53, Fig. 1, to engage the clutch of the upper or lower pinion 13 as the case may be and is then braked by operation of lever 57 so that the rotation of pinions 12 about the axis of rotation of the rotor produces rotation about their own axes. The radial position of the blades may be given by an indicator 80. A modified rotor head construction is shown in Fig. 12, in which the main body of the head is spherical and is stepped at 90 to receive a ballthrust bearing 91 on which rests flange 3a of driving shaft 3, both step and flange being integral with the respective members. In a modified drive mechanism for the blade gear, crown wheels 13 are fixed on shaft 14, the clutches being omitted. For effecting pitch control, gear spindle 34 is keyed to the rotor head by engagement of a cross pin 93 in slots formed in a cylindrical projection 94, the cross pin carrying a sleeve 92 formed with cam slots engaging pins 31. In both forms described, the rotor head is drivable in any adjusted position and is capable of limited axial movement, but provision either for this movement or for altering pitch or blade length may be dispensed with. According to a modification, the driven member of the drive coupling may be connected directly to the head by a one-way drive.